Tech uses call forwarding to detect robocalls before they reach their targets.

A new technology called "RoboKiller" has won a $25,000 grand prize from the Federal Trade Commission in the agency's "Robocalls: Humanity Strikes Back" contest aimed at promoting technologies to block and defeat the scourge of automated telemarketing systems. While it's still in testing, the Robokiller application could give both mobile and landline phone customers a shield against unwanted robocalls, as well as a way to sort through them like e-mails in a spam folder.

For the past few years, the FTC has held competitions to promote development of technology that can detect and block robocalls—the increasingly sophisticated computerized phone calls that all too frequently are used by scammers to fish for gullible consumers. Ignoring the FTC's "Do Not Call" list, these systems use a number of methods to avoid detection, including using voice-over-IP lines with numbers local to targeted numbers and interactive voice response systems scripted to act like human operators.

Ars met with Ethan Garr, the cofounder of RoboKiller, at DEF CON earlier this month, where RoboKiller took part in the final round of the FTC's competition for 2015. Garr explained in a nutshell how RoboKiller works:

Users register their phone number with the RoboKiller app, which forwards all incoming calls through RoboKiller's backend in a cloud data center.

The RoboKiller server analyzes the incoming call, "answering" the call but still playing a ring signal before connecting the call.

Robocalls detect the initial answer by RoboKiller's server and will start their recorded message. Humans will hear ringing and wait for the user to answer. RoboKiller's server performs audio analysis on the back-end, looking for signs that it is a robocall—blocks of silence with no background noise and other audio signatures that are associated with automated calls.

Robocalls will get routed directly to a spam bucket. Calls determined to be from live callers will be forwarded as SIP calls to the app user.

RoboKiller and a runner-up technology from Hemant Sengar (based on a similar audio analysis approach) are the first winners of the FTC competition that try to directly screen incoming calls. Winners in previous competitions largely focused on creating robocall "honeypots" to gather data on patterns in automated calls, creating signatures based on the calls that could be used to assess whether an incoming call was a robocall based on its source number—much like the reputation databases used by anti-malware products to block malicious Web downloads.

Unfortunately, Ars hasn't been able to directly test RoboKiller yet—we're still in queue to get our beta account activated. But once we're live, we'll provide a full review. In the meantime, you can get early access to RoboKiller through the project's Kickstarter page.

Sean Gallagher
Sean is Ars Technica's IT and National Security Editor. A former Navy officer, systems administrator, and network systems integrator with 20 years of IT journalism experience, he lives and works in Baltimore, Maryland. Emailsean.gallagher@arstechnica.com//Twitter@thepacketrat